Poly(2-hydroxyethyl methacrylate) (hereinafter referred to as polyHEMA in some case) has been evaluated as a polymer which is relatively excellent in biological affinity or biocompatibility, and ABA type block copolymer containing HEMA segment in the molecule is further proposed for a biocompatible medical material (for example, refer to Japanese Patent Application Laid-open No. Sho 55-50028). Moreover, the specific applications of such block copolymer as the medical material, for example, the applications to an artificial blood vessel (Japanese Patent Application Laid-open Nos. Sho 58-175553, 60-31762, 60-34451), a medical suture (Japanese Patent Application Laid-open No. Sho 60-31761), and the like are proposed, and another ABA type block copolymer is also proposed (e.g., Japanese Patent Application Laid-open Nos. Sho 61-236831, 60-232166).
The former group of publications describe the block copolymer in which segment B is a segment derived from polyalkylene oxide having isocyanate groups on opposite terminal ends, and segment A is a segment derived from a)-hydroxyalkyl acrylate. Japanese Patent Application Laid-open No. Sho 61-236831 describes the block copolymer in which segment B is a segment derived from polystyrene having isocyanate groups on opposite terminal ends, and segment A is a segment derived from polyhexyl acrylate.
Moreover, the latter Japanese Patent Application Laid-open No. Sho 60-232166 describes ABA type block copolymer composed of blocks A and B which are both hydrophobic blocks but differ from each other in hydrophobic degree. Additionally, the block A is derived from (meth)acrylic ester having a polyfluoroalkyl group, while the block B contains polystyrene, polybutadiene segments. For these block copolymers, the applications as anticoagulant materials are also proposed.
According to Japanese Patent Application Laid-open No. Sho 55-50028 which belongs to the former group of publications, it is suggested that the block copolymer can form hydrophilic and hydrophobic domains in solution in the state where molecules are getting together, i.e., it can form a micro phase separation structure, so that the biocompatibility can be provided.
As described above, various types of polymers have been developed particularly for medical biocompatible materials, and some of the polymers appear to realize the object of the development to some degree.
However, the conventional material are not necessarily satisfactory for the construction of a blood compatible or biologically compatible surface on various medical devices such as an artificial heart, a dialysis membrane, an artificial lung, a contact lens, a catheter, and the like. Therefore, an object of the present invention is to provide a material superior in blood compatibility or biological compatibility.